1. Field of the Invention
The present invention relates to a motor, a fuel pump, a commutator, and a method for manufacturing a commutator.
2. Description of the Related Art
Motors are known that use a commutator having a plurality of segments disposed in a circular fashion in the direction of rotation and that are electrically connected with coils wound around an armature, such that drive current supplied to the armature is converted by brushes that successively contact the segments accompanying rotation of the armature. Japanese Patent Publication No. Hei 7-85642 discloses such a motor.
In this sort of motor, there are sometimes occurrences of discharge between a brush and the segments when the segments separate from the brush accompanying rotation of the armature due to electromagnetic energy built up in the coils being released. When discharge occurs between the brush and the segments, there is the possibility of the brush and the segments suffering discharge wear, leading to poor electrical contact between the brush and the segments. It is another object of the present invention to provide a motor, a fuel pump, a commutator, and a method for manufacturing a commutator, which is capable of preventing discharge wear of the brush and the segments thereof.
Many motors have a plurality of segments disposed in the direction of rotation and are electrically connected to coils wound around an armature, and convert drive current which is supplied to the armature by brushes that successively contact each segment accompanying rotation of the armature. Among such motors, there are known configurations wherein segments of the same potential are electrically connected together.
For example, according to Japanese Patent Laid-Open Publications No. 2000-166185, No. 2000-60073, No. 2000-60074, and No. 2000-224822, a plurality of connection terminals are layered in the axial direction alternately with insulation plates interposed therebetween, with equalizers disposed at each connection terminal so as to extend in the radial direction to the opposite side. Per each connection terminal, equalizers disposed at differing positions in the direction of rotation are bent toward the segments, and segments of the same potential are electrically connected together by the equalizers.
According to Japanese Patent Laid-Open Publication No. 2000-60077, mutually insulated printed wiring boards are layered in the axial direction, and connecting plates are formed on each printed wiring board at differing positions in the direction of rotation per each printed wiring board. Protrusions projecting from segments of the same potential pass through the printed wiring boards to electrically connect to connecting plates of the printed wiring boards in corresponding layered positions.
However, with the aforementioned examples disclosed in the patent publications, since connection terminals or printed wiring boards are layered in the axial direction with insulation plates or insulation boards interposed therebetween to connect segments of the same potential, the axial length of connectors for electrically connecting segments of the same potential is long. Accordingly, the axial length of the motor is adversely long.